Abstract
A coherent-noncoherent joint processing framework is proposed for active sonar to combine diversity gain and beamforming gain for detection of a small target in shallow water environments. Sonar utilizes widely-spaced arrays to sense environments and illuminate a target of interest from multiple angles. Meanwhile, it exploits spatial diversity for time-reversal focusing to suppress reverberation, mainly strong bottom reverberation. For enhancement of robustness of time-reversal focusing, an adaptive iterative strategy is utilized in the processing framework. A probing signal is firstly transmitted and echoes of a likely target are utilized as steering vectors for the second transmission. With spatial diversity, target bearing and range are estimated using a broadband signal model. Numerical simulations show that the novel sonar outperforms the traditional phased-array sonar due to benefits of spatial diversity. The effectiveness of the proposed framework has been validated by localization of a small target in at-lake experiments.
Highlights
Signal fading due to target scintillation can cause large degradations in detection and estimation performance of the sonar system
We consider a sonar system consisting of M vertical transmitting arrays that are widely-spaced to illuminate a target from multiple angles
We have proposed a coherent and noncoherent jointly sonar processing framework to combine spatial diversity gain with beamforming array gain for active detection
Summary
Signal fading due to target scintillation can cause large degradations in detection and estimation performance of the sonar system. Improvement of target detection is achieved through exploiting advantages of continuous illumination and spatial diversity [2]. We focus on coherent and non-coherent joint processing to achieve beamforming array gain and spatial diversity gain for improvement of detection performance of the traditional phased-array sonar. Due to building on the plane wave propagation model, phased-array sonar rarely utilizes vertical diversity for target detection. The vertical diversity is exploited by the time-reversal (TR) mirror [15,16,17,18,19,20,21,22,23] to enhance target echoes and suppress reverberation by spatial-temporal focusing.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
